And Some Of It Can't Be Quantified
by Jadzia Bear
Summary: Tony Stark will give pretty much anything a go, but that doesn't mean he expects it to work. Stark Spangled Banner Tony Stark/Steve Rogers/Bruce Banner


_**And Some Of It Can't Be Quantified**_

**OT3:** Stark Spangled Banner (Tony Stark/Steve Rogers/Bruce Banner)

**AN:** I don't really know what to say about this one, except that I really, really enjoyed writing it. Also, I hope you have your insulin handy, because this fic is so sweet and fluffy you just might need it!

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Tony Stark has long considered himself a sexual opportunist. Not opportunistic in a callous sense, just in the sense that if an opportunity presents itself, chances are he's up for it. Anonymous sex in a bathroom stall, kinky toys, an entire cheerleading squad—as long as it's consensual, he'll give pretty much anything a go.

As a result, waking up with two other guys in his bed isn't a brand new experience for Tony. That's not the thing that's bothering him. And it's certainly not the fact that it's happened nearly every night for the last three and a half months.

Bruce likes to sleep on the side of the bed closest to the door; he mentioned it once, back at the beginning. He doesn't often speak up for himself, so when he does, Tony makes sure he gets what he wants. Besides, if sleeping close to an exit is the strongest expression of any latent desire Bruce might have to hightail it back to some third world country, it's a no-brainer.

Tony usually takes the other side. That way he doesn't disturb anyone when he wakes up in the middle of the night with some shiny new idea or a solution to whatever invention he's currently stuck on. He'll slip out and make some notes on a tablet or head down to the workshop for a few hours, then crawl back into bed before dawn.

Fortunately, Steve doesn't seem to mind where he sleeps, and with the way he always runs a little warm (because a four-fold metabolic rate will do that to you), having him in the middle keeps everyone toasty.

Tonight, though, it'd been kind of hot when they'd been ready for sleep (or they'd all been pretty sweaty, at any rate), so Steve and his excess body heat had been relegated to the side nearest the window. Steve had climbed easily over Tony, dropping a kiss on his lips as he went, then rolled over and promptly fallen asleep in that irritatingly effortless way soldiers do. That left Tony in the middle, which is secretly his favourite spot, where he wakes up some hours later.

He's lying on his back, the pale glow of the arc reactor reflecting fainting off the ceiling. The air feels cooler now, and the quilt is still somewhere down around his thighs. He pulls it up to his chest, making an attempt to spread it over the other two as well.

Bruce is facing away from him, curled up, with his back against Tony's left side. Meanwhile, Steve is using Tony's right shoulder as a pillow. The entire length of Steve's body is pressed comfortably against him, and he has one arm thrown over Tony's stomach. Steve is an unabashed cuddler, but so is Tony, so that's fine.

Tony presses a gentle kiss to Steve's forehead, just because he can, and Steve snuggles closer without even seeming to wake up. Tony tightens his arm around Steve, feeling kind of protective—ridiculous, he knows, considering Steve is so much stronger and older than he is.

If he's being honest, he feels protective of Bruce too. The Other Guy may be practically invincible, but Banner is an entirely different creature. Not weak, by any means, but he has his vulnerabilities. "I got low," Bruce had said, and god help him, Tony was going to make sure he never got that low again.

He runs a palm lightly down Bruce's side. Tony intends to leave his hand on Bruce's hip, but the feather-light contact rouses Bruce and he rolls over. After a brief, sleep-softened kiss, he settles his head on Tony's other shoulder.

It shouldn't work, the three of them. Tony should have screwed it up long ago. He can't even make it work with one person (Pepper is the latest in a long line who can attest to that), let alone two.

But maybe Pepper leaving was the straw that finally taught him that sometimes you just fucking apologise, no matter how much you don't want to (and it's no secret Tony does plenty of shit that needs apologising for). It's not like he can't spare that tiny bit of ego that dissolves every time he says the "s" word, and maybe he's finally—_finally_—realised that it's worth it if it keeps the people he cares about from walking out the door.

But there's more to it than just him being less of a douche bag. More than Bruce being such a pro at smoothing the waters, more than Steve making sure he and Bruce don't spend too many consecutive hours in the lab without food or sleep. They work so well together, it's like...

It's like the Lamborghini engine he rebuilt the summer he turned sixteen. He'd re-designed some of the parts, upgraded most of the systems. The final product was intricate, but it was the most reliable motor he'd ever made, and it purred like a goddamn kitten. It couldn't strictly be called a Lamborghini anymore, but it was something better, something unique.

And that's the problem. He can _understand_ an engine; he doesn't understand this. He lies awake some nights, listening to the comforting sound of two sets of slow, rhythmic breathing, attempting to quantify the variables. He tries to examine all the cogs, determine how and why they fit so precisely with all the others. But this isn't mechanics or math or electronics. He doesn't know _how_ it works; only that it does.

The hand on Tony's stomach flexes absently, then Steve reaches a little further until his palm is resting where Tony's had been headed earlier: Bruce's hip. Bruce responds with a contented _hmph_.

Tony is possibly coming up on the conclusion that he should stop thinking so much about the whole situation and just enjoy it, when Bruce murmurs, "Tony, go to sleep," without even opening his eyes.

One side of Tony's mouth ticks up in a smirk. "Yes, dear," Tony answers, because Bruce's ideas are usually good ones.

It defies logic that Tony's wild, anything-goes sex life could have led him to something this perfect, but he couldn't be more glad that it did.

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**AN:** Thanks for reading. Extra points if you noticed that the title is a quote of River's from the show _Firefly _:)


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